• Korean Journal of Heritage: History & Science
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• v.39
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• pp.281-314
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• 2006

Several explanations exist about the usage of disk-shaped bronze implements in the ancient society. Some argue that they were used as mirrors, others suggest percussion instruments, and still others bronze ornaments. Differences between disk-shaped bronze implements and mirrors with multiple knobs are that the former have no visible design, only one handle, and a sharp curvature unlike the latter with smooth curvature. The question is whether disk-shaped bronze implements excavated from Korean peninsula have any light reflecting function. To answer this question, I carefully studied the concave surfaces of disk-shaped bronze implements excavated from Goejeong-dong, Tongso-ri and Hapsong-ri sites. The main findings are as follows: (1) The concave sides of the disk-shaped bronze implements excavated from Goejeong-dong and Tongso-ri sites were highly polished, and they were as reflective as bronze mirrors. (2) The concave side of the disk-shaped bronze implement from Hapsong-ri site was unpolished, and it was different from bronze mirrors. (3) As for the convex sides of the disk-shaped bronze implements, they did not appear to have been polished with care. Considering the above findings, the disk-shaped bronze implements excavated from Goejeong-dong and Tongso-ri sites belong to the stage where they could act as both mirrors and instruments. On the contrary, the disk-shaped bronze implement from Hapsong-ri site can belong to the stage where it lost the function of being a mirror as the result of maintaining only its function as an instrument. Even though disk-shaped implements had two functions, it can be considered that the light reflecting function expanded the role of a mirror with multiple knobs and the sound function helped the engraved round bronze implement to be converted into an eight-armed bronze rattle. Since it has been reported that shamans used bronze mirrors as percussion instruments in their performances in Korean peninsula and Siberia, I propose a reconsideration of the usage of mirrors in the ancient East Asia. Although the essential function of a mirror is to reflect light, other possible usages involving important functions need to be further investigated.

• Bangmulgwan gwa yeongu (The National Museum of Korea Journal)
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• v.1
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• pp.198-233
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• 2024

On April 28, 2021, the bereaved family of the late Samsung Group chairman Lee Kun-Hee made a gift of 9,797 items (in 21,693 pieces) from his estate to the National Museum of Korea. Among the donated cultural heritage are 535 mirrors (in 555 pieces), which constitute the largest proportion of the metal art in the donation. This article discusses a group of mirrors from the donated collection dating to the Western Han and Samhan periods - a total of twenty-three mirrors (twenty-two from the Western Han Dynasty and one from the Samhan Period) - that are presumed to have been found together. However, there is no known case of such a large number of Western Han mirrors being discovered together, raising doubts about whether this group should be considered to have been buried all together. Furthermore, the presence of a Samhan mirror among the group suggests that this one at least must have been found together with a Western Han mirror. Additionally, considering that early Samhan mirrors have been found in the southeastern part of the Korean Peninsula, particularly in the region occupied by Jinhan Confederacy (in present-day Gyeongsangbuk-do Province), it is likely that these mirrors were also excavated somewhere in Jinhan. Also, -18 is a repurposed imitation of a jade eye cover. No similar examples have been found in Korea, China, or Japan, but there are instances of bronze mirrors being used as substitutes for jade burial ornaments that have been identified in China. The repurposing and use of Western Han mirrors as circular ornaments have been observed only in Jinhan in the southern part of the Korean Peninsula, indicating that this item was likely used in Jinhan as well. Further research and discoveries are anticipated in the future.

• International Journal of Contents
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• v.9 no.1
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• pp.60-64
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• 2013

This study was performed for two of specific reasons, one is for exercise development for improving stroke patient's muscle power, balance and gait and, after verifying the effect of the exercise, the other is for showing that the appling this exercise was more effective on hemi-plegic stroke patients into the clinical trial. The subjects of this study were hemi-plegic patients by stroke, 51 patients were picked up, who were agreed with this research. Close kinetic chain leg exercise using mirrors was applied to study group I, Close kinetic chain leg exercise without mirrors was applied to study group II and general physical therapy was applied to comparison group. The results of this study are as follows. The difference of the groups, study group I showed more effective than study group II on checking rectus femoris, vastus lateralis, biceps femoris, Korean version of Berg Balance Scale, Center of pressure, Functional gait assessment. In this study, Close kinetic chain leg exercise showed more effective and significant on improving for muscle power, balance and gait on stroke patients. Especially, doing exercise using mirrors is considered as more effective method than without mirrors.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.91.2-91.2
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• 2014

A near infrared wide-band high resolution spectrograph, immersion grating infrared spectrometer (IGRINS) has been jointly developed by the Korea Astronomy and Space Science Institute and the University of Texas at Austin. The compact white-pupil design of the instrument optics includes five cryogenic flat mirrors including a slit mirror, an input fold mirror, a dichroic mirror, and H&K camera fold mirrors. In this study, we introduce the optomechanical mount designs of the five cryogenic mirrors. In order to meet the structural stability and thermal requirements of the mount models, we conducted the design work with the aid of 3-dimensional computer modeling and the finite element analysis (FEA) method. We also present the actual fabricated parts and assemblies of the mounts and mirrors as well as their CAD models.

• Korean Journal of Geomatics
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• v.1 no.1
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• pp.69-74
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• 2001

In conventional photogrammetry, three-dimensional coordinates are obtained from two consecutive images of a stationary object photographed from two exposure stations, separated by a certain distance. However, it is impossible to photograph moving objects from two stations with one camera at the same time. Various methods to overcome this obstacle were devised e. g. taking the left and right scenes simultaneously with one camera using a beam splitter attached to the front, thus creating a stereo scene in one image. A beam splitter consists of two outer mirrors and two inner mirrors. This paper deals with research where the optical principles of the beam splitter were evaluated based on light path phenomena between the outer mirrors and the inner mirrors. A mathematical model of the geometric configuration was derived for the beam splitter. This allows us to design and control a beam splitter to obtain maximum scale and maximum base-height ratio by stepwise application of the mathematical model. The results show that the beam splitter is a very useful tool for stereophotography with one camera. The optimum geometric configurations ensuring maximum scale and base-height ratio are closely related to inner and outer reflector sizes, their inclination angles and the offsets between the outer mirrors.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.12
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• pp.56-63
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• 2008

In this study, a side inspection system for circular o-ring, bolt, plastic and gasket using 8 side mirrors has been developed. The system is comprised of a CCD camera, an illumination, the first 8 mirrors and the second 8 mirrors, and moreover the image processing algorithm for detecting three different type samples is developed. The effectiveness of this algorithm was experimentally verified with three different type samples, and the inspection process is completed within max 0.2 second by help of smart camera. It is envisaged that this inspection method for side inspection system of a circular will have a wide application in the future industry.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.55.4-56
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• 2018

Linear Astigmatism Free - Three Mirror System (LAF-TMS) is the linear astigmatism free off-axis wide field telescope with D = 150 mm, F/3.3, and $FOV=5.51^{\circ}{\times}4.13^{\circ}$. We report the design and analysis results of its mirrors and optomechanical structures. Tolerance allowance has been analyzed to the minimum mechanical tolerance of ${\pm}0.05mm$ that is reasonable tolerance for fabrication and optical alignment. The aluminum mirrors are designed with mounting flexure features for the strain-free mounting. From Finite Element Analysis (FEA) results of mounting torque and self-weight, we expect 33 - 80 nm RMS mirror surface deformations. Shims and the L-bracket are mounted between mirrors and the mirror mount for optical alignment. The mirror mount is designed with four light-weighted mechanical parts. It can stably and accurately fix mirrors, and it also suppresses some of stray light.

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.187-188
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• 2007

Four kinds of mirror substrates with same surface roughness were fabricated. On those substrates, a dielectric multi-layer coating with high reflectivity was deposited by ion beam sputtering technique. Most of the fused silica mirrors showed lower scattering than the ZERODUR mirrors one, which deposited on substrates similar in surface roughness. The ZERODUR mirrors scattering strongly depend on the micro-structure of $Ta_2O_5/SiO_2$ thin films wear deposited on ZERODUR substrates.

• Korean Journal of Optics and Photonics
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• v.9 no.2
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• pp.92-95
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• 1998

In this paper, we have shown theoretically that a nonlinear etalon with nonlinear mirrors exhibits optical bistability. It can be swithed with less power than a nonlinear etalon with linear mirrors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.336-339
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• 1995

There has been considerable interest in electrochromic devices because of its potential application in automobiles including mirrors and windows. The electrochromic(EC) mirror can automatically control the amount of glare produced by headlights or other light source on either inside or outside mirrors. Therefore, the EC mirror can be a better alternative to todays day-night mirrors for automobiles. In this paper we have fabricated all solid state EC mirrors with glass-ITO / a-WO$_3$/ polymer electrolyte / a-V$_2$O$\sub$5/ / ITO-glass / Al structure and investigated their spectral reflectance as a function of applied voltage.